Ultrastructural characterisation of Bacillus subtilis TatA complexes suggests they are too small to form homooligomeric translocation pores.
Ultrastructural characterisation of Bacillus subtilis TatA complexes suggests they are too small to form homooligomeric translocation pores.
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DOI：
10.1016/j.bbamcr.2013.03.028
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发表时间：
2013-08
影响因子：
5.1
通讯作者：
Smith, Corinne J.
中科院分区：
文献类型：
--
作者：
Beck, Daniel;Vasisht, Nishi;Baglieri, Jacopo;Monteferrante, Carmine G.;van Dijl, Jan Maarten;Robinson, Colin;Smith, Corinne J.
关键词：
依赖于tat的蛋白质运输允许完全折叠的蛋白质在细菌和叶绿体中的跨膜运输。发生这种情况的机制尚不清楚。目前的理论认为，关键的一步需要结合底物的含tatc复合物与TatA复合物结合，形成不同大小的孔，可以容纳不同的底物。我们利用电子显微镜研究了枯草芽孢杆菌的TatAd复合体的结构，生成了革兰氏阳性细菌的TatA复合体的第一个3D模型。我们观察到TatAd没有表现出大肠杆菌TatA配合物的显著异质性，而是形成了直径7.5-9 nm的环状配合物，其潜在孔直径为2.5-3 nm，一端被封闭。这种结构与大肠杆菌TatE复合物的结构一致。此外，TatAd孔的小直径和配合物的均质性表明TatAd不能自行形成转运通道。生化数据表明，另一种枯草芽孢杆菌TatA复合物TatAc具有类似的性质，这表明芽孢杆菌TatA型复合物具有共同的主题。来自革兰氏阳性菌的塔塔型配合物的首个三维密度图TatAd形成环状配合物，其潜在孔隙直径为2.5 - 3nm。TatAd通道的小直径显然阻碍了折叠蛋白的通过。TatAc形成< 100kda的均相配合物。枯草芽孢杆菌TatAd和TatAc之间的相似性表明它们具有共同的机制。
Tat-dependent protein transport permits the traffic of fully folded proteins across membranes in bacteria and chloroplasts. The mechanism by which this occurs is not understood. Current theories propose that a key step requires the coalescence of a substrate-binding TatC-containing complex with a TatA complex, which forms pores of varying sizes that could accommodate different substrates. We have studied the structure of the TatAd complex from Bacillus subtilis using electron microscopy to generate the first 3D model of a TatA complex from a Gram-positive bacterium. We observe that TatAd does not exhibit the remarkable heterogeneity of Escherichia coli TatA complexes but instead forms ring-shaped complexes of 7.5–9 nm diameter with potential pores of 2.5–3 nm diameter that are occluded at one end. Such structures are consistent with those seen for E. coli TatE complexes. Furthermore, the small diameter of the TatAd pore, and the homogeneous nature of the complexes, suggest that TatAd cannot form the translocation channel by itself. Biochemical data indicate that another B. subtilis TatA complex, TatAc, has similar properties, suggesting a common theme for TatA-type complexes from Bacillus. First 3D density maps of TatA-type complexes from Gram-positive organism TatAd forms ring-shaped complexes with potential pores of 2.5–3 nm diameters. The small diameter of TatAd channels apparently precludes passage of folded proteins. TatAc forms homogeneous complexes of < 100 kDa. Similarities between B. subtilis TatAd and TatAc suggest a common mechanism.
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DOI：
10.1073/pnas.0806338105
发表时间：
2008-10-07
影响因子：
11.1
作者：
Leake, Mark C.;Greene, Nicholas P.;Berks, Ben C.
通讯作者：
Berks, Ben C.
影响因子：
3.6
作者：
Jongbloed, JDH;Grieger, U;van Dijl, JM
通讯作者：
van Dijl, JM
影响因子：
3.4
作者：
Lange, Christian;Mueller, Sonja D.;Ulrich, Anne S.
通讯作者：
Ulrich, Anne S.
影响因子：
3.4
作者：
Nolandt, Olga V.;Walther, Torsten H.;Ulrich, Anne S.
通讯作者：
Ulrich, Anne S.
影响因子：
15
作者：
Hu, Yunfei;Zhao, Enwei;Jin, Changwen
通讯作者：
Jin, Changwen